Self-sharpening rotary-drill bit



Jan. 17, 1928. 1,656,511

7 J. DAHL I SELF SHARPENING ROTARY DRILL BIT Filed Aug. 14, 1925 A TTORNE Y.

Patented Jan. 17, 1928.

UNITED STATES JOHN DAHL, F DALLAS, TEXAS.

SELF-SHARPENING RiOTARY-DRILL 311.

Application filed August 14, 1925. Serial 170. 50,158.

This invention relates to well tools and I equipment and it has particular reference to new and useful improvements in selfsharpening rotary drill bits, the primary object being to provide, through its novel construction, certain expediences for dispensing with accumulations of dirt, gumbo and other sticky formations, which causes the ordinary fish tail bit to ball-up and resulting in otherwise hindering the proper performance of the bit.

The invention further contemplates a drill bit having interchangeable blades, which blades are arranged to be retained in the shank in such a manner that the natural frictional-wear and pressure imposed thereupon may be automatically assumed to man tain positive rigidity and proper operating position of the blades.

Further, the invention contemplates a shank which is constructed principally on straight lines, and in which no twists or concave pockets are incorporated, thus further insuring proper performance of the tool, by the elimination of possible accumulations of mud, gumbo and the like therein.

Still further, the invention comprehends among its ob ects, a locking means for each of its cutting blades, whereby to positively avoid dislocation of these elements during rotation of the bit within'the well, due to or fouling of projecting nuts or bolts while the tool is being withdrawn or lowered into the well.

With the foregoing and other objects and advantages in view, the invention further comprehendscertain novel features of construction and assembly of which the said objects are which will be set forth and the course of the following tion, and illustrated in the drawings, wherein Figure 1 represents a view of the shank attained, and manifested in detail descripaccompanying in vertical elevation, from which the'cutting blades have been removed, illustrating the curvature of the body to facilitate passage of dirt thereby.

Figure 2 is a similar view, showing the blades in proper position within the shank,

and illustrating the securing arrangement therefor.

Figure 3 is a view in vertical section, illustrating the position of the water courses in the shank.

Figure 4 is an elevationalside view of elements, by

tively rigid.

the bit, showing the self tightening features of the blades. c

Figure 5 represents a plan view of the invention, depicting the straight line diametrical principle on which the shank is constructed.

Figure 6 is a bottom view of the invention, from which the blades have been removed, further illustrating the curvature of the shoulders ofthe shank.

Figure 7 is a sectional view of the blades, showing a detail view of the self sharpening arrangement thereon on lines 7 7 of Figure 8, and,

Figure 8 is .a detail view of one of the blades.

In proceeding in accordance with the foregoing, 1 denotes the body or shank of the drill, which is provided with set-back shoulders 2. These shoulders, it will be observed in Figures 1 and 2, are formed to effect a normally curved surface on either side of the shank 1,. terminating in a moderately curved port-ion adjacent the upper portion of the shank. The advantage of this par ticular feature will be later made clear. The shank 1 is further provided with opp0- sitely disposed flattened surfaces a, forming in part, cavities in which spaced tapered channels 6 are cut to receive conformably tapered projections 0 on the blades 3.

. Constant rigidity of the blades 3 in their respective positions is accomplished in the manner illustrated preferably in Figure 4. A protruding lip 4 is provided at the upper portion of the flattened surfaces 0:, which latter depends over the said surfaces, affording the cavity hereinbefore mentioned. The end of the blade 3 is thrust beneath this protruding lip 4:, and in addition to the tapered projections c, the resiliency of the blades, through constant jarring in operation, causes the latter to move upward and be received by the cavity formed by the protruding lip 4, thus rendering the blades posi- As a further insurance against dislocation of the blades 3, a locking means comprising a bolt 5, provided with a tapered stud, is inserted through an aperture 5, whereby the said stud may be received jointly by the squared slots 5 in the edges of the flattened surfaces at and the blades 3, thus to aid in pressing the blades upwardly into the cavity, beneath the lip 4, upon tightening of the bolt 5.

In addition to the foregoing locking the sides of means, a bolt 6 is arranged to be inserted through the apertures 6 in the shoulders 2, in such a manner as to be received by the elongated slot 6 in the tapered projections 0 on said blades.

In the usual construction of drill bits, a disadvantage accruing from improper distribution of water, is the heating of the blades resulting in softening of the metal and by which they readily become dull and require to be withdrawn for renewal. This procedure is obviously very expensive. The water courses 7, provided in the present invention aims to obviate this fault by affording water courses disposed at angles whereby to provide a constant flow of water on a level with the flat side of each of the blades. The preferred angle or disposition of these water courses may be readily observed in Figure 3. In addition to a cooling means for the blades, the pitch of these courses is arranged to continuously wash the blades and prevent accumulations of mud and other extraneous substance thereon, and further to avoid disintegrating the gauge of the hole formed by the blades.

As a further expedient of the blades 8, to insure greater operating time of the bit, an inlaid layer of hardened steel 8 is welded or otherwise suitably ailixed to the cutting surface of each of the blades, the body of the blades being of softer metal, rotation of the bit in the natural cutting angle thereof will frietionally grind the metal away according to its hardness, resulting in a perpetual cutting edge at the proper angle, as illustrated in Figure l. The outer edge of the inlaid layer of metal 8 is formed into a ridge 9, as shown in Figure 7. This arrangement not only produces a cutting gauge whereby to hold the gauge of the hole, but also directs the slush inwardly to permit the same to be readily conveyed upwardly past the shank 1, by the peculiar curvature of the shoulders 2, in addition to its advantage in strengthening the point and making it possible to keep the balance of the cutting surface of the blade thinner, which will obviously expedite the cutting qualities of the blade.

A dominant feature of the present invention is the mounting of the blades in diametrical alinement, as illustrated in Figure 6. The resulting action produced by this particular arrangement is more or less a olting rather than reaming or sliding action, combined with the rotary motion thereof. The blades 3 are thus, less likely to become heated, to impair the condition of their metal, and affords in addition, a greater drilling capacity for the bit.

The invention has been described as including all the elements set'forth in the appended claims, however, should it be desired to alter certain elements in the assembly as set forth, it should be herein understood that such alterations may be resorted to as fall within the scope of the invention and within the meaning and breadth of the following claims 1. In a drill bit, the combination comprising a shank having shoulders set backwardly of a diametrical line to afford a moderately curved surface terminating adjacent its top; blades removably mounted in said shoulders, means for tensioning and holding said blades under tension in said shoulders, and means to cause the slush to be directed inwardly and conveyed upwardly above said shank by said shoulders.

2. A drill bit having opposed diametrically alined cutting blades mounted in a shank having inset shoulders; means to effect tensioning of said blades within said shank, means for holding said blades under such tension; and means to effect inward divergence of slush produced by said blades to be carried upwardly by said shoulders.

In testimony whereof I affix my signature.

JOHN DAHL. 

